Went to all Euro games. Tickets loaded via UEFA app. I bought spares and the app allowed as many transfers as I needed to share tickets with friends and family (no charge). They just needed to have the app as well. Covid checks at the games were same guidelines and level as I've encountered with my ST at Amex. Simple, no fuss sharing, and same box ticked about knowing who had them. Obviously there were other event management issues but the basic ticketing scheme worked.